Measuring your pelvis size for bodybuilding is straightforward: wrap a tape measure around your hips at the widest point of your pelvis, roughly where you’d wear your pants. This single circumference measurement is the foundation of classic proportion systems like Steve Reeves’ ideal physique formula, and it tells you something important about your genetic frame that no amount of training will change.
What You’re Actually Measuring
In bodybuilding, “pelvis size” refers to the circumference of your hips at the level of the iliac crest, the bony ridge you can feel at the top of each hip bone. This is different from what anthropologists measure. Researchers distinguish between bi-iliac breadth (the straight-line distance between the outermost points of the iliac crests) and bi-trochanteric breadth (the distance between the bony bumps at the tops of your thigh bones). Both of those require sliding calipers and measure bone width only.
For bodybuilding purposes, you don’t need calipers. The tape measure circumference captures bone width, muscle mass, and a small amount of soft tissue all at once. That composite number is what proportion formulas are built around.
How to Take the Measurement
Stand in front of a mirror with your shirt off or pulled up above your waist. Place your hands on your hips and feel for the iliac crest on each side. It’s the curved bony ledge that runs from the front of your hip toward your lower back. The highest, most prominent point is your landmark.
Wrap a flexible cloth tape measure around your body at that level, keeping it parallel to the floor all the way around. The tape should sit snugly against your skin without compressing the tissue underneath. Don’t suck in your stomach or flex your glutes. Stand relaxed with your feet about hip-width apart, and take the reading at the end of a normal exhale. Measure three times and use the average.
Body fat matters here. Subcutaneous fat sitting on top of the iliac crest inflates the number, so the measurement is most useful when you’re relatively lean. To get a sense of how much fat is padding the reading, pinch the skin just above the iliac crest between your thumb and index finger and pull it away from the muscle. If you’re grabbing more than a thin fold, your circumference includes a meaningful amount of fat tissue. The classic Reeves formulas assume a lean condition, roughly 8 to 12 percent body fat.
Steve Reeves’ Proportion System
Steve Reeves built one of the most famous proportion systems in bodybuilding history around the pelvis measurement. His formulas use your pelvis circumference as the anchor point for two key ratios:
- Waist: 0.86 times your pelvis size
- Chest: 1.48 times your pelvis size
So if your pelvis measures 38 inches, a “proportional” waist would be about 32.7 inches and your chest would target 56.2 inches. Reeves also believed your arms, calves, and neck should all be the same circumference, though those aren’t pegged to pelvis size directly.
These numbers are aspirational targets, not pass/fail thresholds. They describe a visual balance between upper and lower body that most people find aesthetically pleasing. The pelvis measurement anchors the system because it’s the one number you can’t meaningfully change through training. Your skeleton sets the floor.
Why Pelvis Width Is a Genetic Fixed Point
Your pelvic bone structure is determined by genetics and finishes developing by your early twenties. You can’t widen it, narrow it, or reshape it. As bodybuilding coach Eric Helms of 3D Muscle Journey has noted, the biggest visual differences between competitors with similar muscle mass often come down to ribcage shape relative to pelvis width. A narrow pelvis paired with a wide ribcage creates a naturally dramatic taper. A pelvis that’s close to the same width as the ribcage requires more strategic muscle development to create the same illusion.
This is why measuring matters. Knowing your actual pelvis circumference tells you which proportions are realistic for your frame and where you need to focus your training to create the visual effect you want.
Working With Wide Hips
A wider pelvis doesn’t disqualify you from a V-taper. Jay Cutler, a four-time Mr. Olympia, was famously wide-hipped. Arnold Schwarzenegger also had a broader pelvis than many realize, which is why he often twisted his hips slightly to the side in front poses to create a narrower visual line.
The key ratio is shoulder width to hip width. As long as your skeletal shoulder structure is wider than your pelvis, you can build a taper. Building up your lats, side delts, and chest widens the top of the frame. Staying lean through the midsection sharpens the contrast. Some competitors with wide hips also find that training their obliques actually helps, because instead of an hourglass shape where the waist pinches in and the hips flare out, developed obliques fill in the gap and create a straighter Y-shaped line from shoulders to hips.
Other competitors take the opposite approach, avoiding heavy oblique work so the waist stays as narrow as possible. Which strategy works better depends on your specific proportions. If your pelvis flares noticeably wider than your natural waistline, building the obliques can smooth that transition. If your waist and pelvis are already close in width, keeping the obliques minimal preserves whatever taper you have.
Bone Width vs. Circumference
If you want to isolate your actual skeletal width from the circumference measurement, you can get a rough estimate. Stand in front of a mirror, place your fingers on the outermost points of your iliac crests (the widest bony points you can feel on each side), and have someone measure the straight-line distance between your fingertips with a ruler or tape. This gives you an approximation of your bi-iliac breadth.
This number is useful for understanding your frame size independent of body fat or muscle. Average bi-iliac breadth for adult men is roughly 28 to 30 centimeters (about 11 to 12 inches), though there’s significant individual variation. Women tend to have relatively broader pelves, particularly at the bi-trochanteric width, which sits lower and includes the hip joint.
For bodybuilding proportion calculations, stick with the tape measure circumference. The Reeves formulas and most modern proportion guides are calibrated to that number, not to bone width alone. But knowing your skeletal measurement helps you set realistic expectations for how narrow your hips can look even at very low body fat.